is the Hull Shape of a boat that
determines the nature of the vessel.
It is fundamental to her size, stability, seaworthiness, speed through
water and maneuverability.
Building, restoring and maintaining even the smallest wooden boat takes
deal of effort, so it is worth
making sure that you
chose a hull shape to suit your needs.
hard-chined Hull Shapes.
hulls are those built from
flat sheets set at an angle to each other.
These are among the easiest hulls to build and are the basis of most
There are three basic categories of chined hulls;
Broad flat bottoms are
However, this flat, bottom will give a rough ride at high speed.
So, this type of hull is most suitable for low speed boats, such
dories and dinghies or where shallow draft is a must.
Many flat bottomed dories have successfully been rigged for sailing by
The flat bottom hull is one of the easiest hull to build.
And because they are easy to build, they are likely to be
other hull shapes.
They have excellent initial stability as well as a great deal of
A deep V is another
simple hull to
However, deep V hulls tend to pitch more than any other hull shape,
if they have canoe sterns.
Most successful V bottom boats are a modification on the basic V.
While the pointed bow will slice through the waves, the aft end needs
flatten out towards the transom to soften the pitching.
Some "V"-bottom power boats have the very bottom flattened to allow it
The hull of a hard chined power boat, like the flat bottomed boat has
However, the V bottom is generally stronger and is much better at
These hulls use more but
narrower boards in
an attempt to compromise between hard chine and rounded
bottom hulls are usually
the round bilge is the
most versatile hull shape it is also more difficult to build and
hull shapes however
tend to be more maneuverable at slow speeds.
hulls range from U or
barrel shape to wine glass and Y shapes.
a keel and either a
skeg or deadwood at the aft end this hull shape will roll and be
are also many hull
designs which are a compromise between the round and hard chined in an
to gain the best from both shapes.
hulls are those where the hull
is supported exclusively or predominantly by buoyancy.
other words the hull
pushes through the water rather than skimming over the top as in a
means that their speed
is dependent on the waterline length.
speeds vary at around 1
to 1.5 times the square root of the waterline length.
is a measure of
the amount of water displaced by the hull, this also determines the
hulls combine speed with sea-worthiness.
they depend on buoyancy
at slow speeds they are capable of developing a moderate amount of
at higher speed.
they are a
combination of a V shape at the bow which becomes a flatter bottom
bilge chine is normally
quite pronounced for stability and ease of building.
hulls are designed to run on
the surface the water at high speeds.
lift generated at
speed raises them, which reduces area of the wetted surface thus
most common design will
have at least one chine to help planing.
in gaining speed
this hull shape will forfeit maneuverability at slow speed, will be
to leeway and pound on waves.
will also require extra
power to get it up onto the plane.
hull shapes vary from
flat bottomed, to V bottomed and sometimes even a rounded bilge.
of the main advantages of the multi hull
is its stability.
sailing proa for instance
would be completely unstable without its outrigger.
are also performance
slow speed a multi hull
with the same total displacement as a mono-hull will be less efficient
is a greater wetted surface area.
the multi-hull will
be less prone to heel.
higher speeds the
narrowness of the hulls, compared to the beam, will allow for an
trimaran is often an
attempt to combine stability with a more capacious main hull.
between the hulls with a wider platform will increase stability and
accommodation but brings with it the problem of structural strength.
don't forget that
the mooring charges for multi hulls are generally higher than foe mono
shape of the hull above the waterline will also have an effect
on how she handles.
as with most things on a
boat there is an amount of compromise to be made.
freeboard will add
windage and leeway, however, it will increase the size of the
load carrying ability.
carrying is important
factor for cruising boats.
topsides especially at
the bow are not just for looks.
also help to reduce
extra buoyancy in the
flare helps to stop the bow digging in as it cuts through the waves.
reason for having
more beam and buoyancy aft is because often that is where much of the
such as engines and people in the cockpit, tends to be
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